Prior to attaching a head gimbal assembly (HGA) into a disc drive, it is desirable to test the functionality of the read and write transducers that reside on the HGA. HGAs that pass testing are permanently mounted to an actuator in the disc drive, such as by swaging an embossment (“boss”) attachment feature of the HGA within an aperture in the actuator. Testing of an unmounted HGA (UHGA) must be done in a manner that preserves the attachment feature for subsequent mounting in the disc drive. Testing the UHGA is necessarily a high speed, highly automated, non-destructive testing process. Because UHGAs are small, fragile, and contain sensitive electronic components, they are susceptible to mechanical stress, electro-static discharge (ESD), environmental contamination, and other handling-related issues.
The testing process includes preliminary activities to align, configure, and prepare the UHGA for testing, followed by functionally testing the UHGA. Details of an apparatus and method for fixturing and testing the UHGA are disclosed in copending application US 2007/0143057, which is assigned to the assignee of this application and is incorporated by reference herein in its entirety. The UHGA must be aligned with respect to its operable read/write position, and then a head set operation is performed in which the UHGA is passed through a magnetic field to properly set the direction of the magnetic domains of the read and write transducers inside the head of the UHGA.
Initially, the UHGA's read and write transducers are electrically shorted together with a shunt tab, which resides on a flex circuit of the UHGA and protects the UHGA from ESD damage by ensuring that the components are held at a common voltage potential. This shunt tab must be broken or removed prior to functionally testing the UHGA. During the functional testing, the UHGA's flex circuit electrically interconnects the transducers to a preamplifier like that in the disc drive, the UHGA is loaded to a test disc, and data transfer testing is performed.
As the areal density increases with which data is stored to the disc, the transducers must be flown lower and more precisely than in the past. Variation in static positioning, such as in roll static attitude (RSA) and pitch static attitude (PSA), that in the past could be ignored as negligible now comes to the forefront as issues that must be addressed. The way the UHGA is non-permanently mounted for testing must also receive greater scrutiny to ensure that any parasitic resonance to the suspension and, in turn the head, of the UHGA is minimized.
The need to robustly mount the UHGA for testing and the need for a highly automated process are competing goals. Intermediate fixtures have been used in some previously attempted solutions, but there are adverse costs associated with loading, purchasing, and maintaining the extra tooling, and the intermediate mounting fixtures also create a larger mass and require an additional mechanical interface, both of which create other potential sources of positional variation and vibration during testing.
Improvements are needed in the manner in which the UHGAs are non-permanently fixtured during testing. It is to improvements in the art directed to solving that need that the present embodiments are directed.